Power converter with a high conversion ratio

ABSTRACT

The present document describes a power converter configured to provide energy at an output based on energy provided at an input. The power converter comprises a first switch, wherein a first node is coupled to the input and wherein a second node is coupled to an intermediate point, a second switch, wherein a first node is coupled to the intermediate point and wherein a second node is coupled to an inductor point, a capacitor, wherein a first node of the capacitor is coupled to the intermediate point, a first diode element, wherein a first node is coupled to a second node of the capacitor and wherein a second node is coupled to the inductor point, a second diode element, wherein a first node is coupled to a reference port, and wherein a second node is coupled to the second node of the capacitor; and an inductor, wherein a first node is coupled to the inductor point and wherein a second node is coupled to the output.

This application is a Divisional application of (DS18-131S) U.S.application Ser. No. 16/568,803 filed on Sep. 12, 2019, owned by acommon assignee and which is herein incorporated by reference in itsentirety.

TECHNICAL FIELD

The present document relates to DC/DC power converters. In particular,the present document relates to power converters providing a relativelyhigh voltage conversion ratio. In particular, the present documentrelates to a resonant power converter with high conversion ratio.

BACKGROUND

A DC/DC power converter is configured to convert electrical power at aDC (direct current) input voltage into electrical power at a DC outputvoltage. Various different techniques may be used for achievingrelatively high conversion ratios between the input voltage and theoutput voltage, such as multi-level converters, transformer step-downconverters, multi-stage converters, a cascade of converters, etc. Thesetechniques are relatively complex with regards to the number and/or thesize of external components, with regards to electromagneticinterference (EMI) requirements, with regards to PCB (printed circuitboard) size, and/or with regards to timing control of the one or moreswitches of the power converter, notably for relatively low loadcurrents to be provided at the output of the power converter.

SUMMARY

The present document addresses the technical problem of providing anefficient power converter for relatively high voltage conversion ratios,notably in case of relatively low load currents.

According to an aspect, a power converter (notably a step-downconverter) configured to provide electrical energy or power at an outputport based on electrical energy or power provided at an input port. Thepower converter comprises a first switch, wherein a first node of thefirst switch is coupled to the input port and wherein a second node ofthe first switch is coupled to an intermediate point. Furthermore, thepower converter comprises a second switch, wherein a first node of thesecond switch is coupled to the intermediate point and wherein a secondnode of the second switch is coupled to an inductor point. In addition,the power converter comprises a capacitor, wherein a first node of thecapacitor is coupled to the intermediate point. The power converter alsocomprises a first diode element, wherein a first node of the first diodeelement is coupled to a second node of the capacitor and wherein asecond node of the first diode element is coupled to the inductor point.In addition, the power converter comprises a second diode element,wherein a first node of the second diode element is coupled to areference port, and wherein a second node of the second diode element iscoupled to the second node of the capacitor. Furthermore, the powerconverter comprises an inductor, wherein a first node of the inductor iscoupled to the inductor point and wherein a second node of the inductoris coupled to the output port. In a preferred example, a diode elementis implemented as an active diode and/or as a switch (notably using atransistor). Hence the term “diode element” may be understood asrepresenting an active diode and/or as being a switch. A diode element(notably a diode), if replaced by a synchronous FET switch, may make useof an asymmetric device for smaller area, faster switching and improvedefficiency. Hence, a diode element may be or may comprise a passivediode (e.g. a Schottky diode), an active diode and/or a switch.

According to another aspect, a power converter (notably a step-upconverter) configured to provide energy at an output port based onenergy provided at an input port is described. The power convertercomprises a first switch, wherein a first node (e.g. the source ofdrain) of the first switch is coupled to the input port and wherein asecond node (e.g. the drain or source) of the first switch is coupled toan intermediate point. Furthermore, the power converter comprises asecond switch, wherein a first node (e.g. the source or drain) of thesecond switch is coupled to the intermediate point and wherein a secondnode (e.g. the drain or source) of the second switch is coupled to areference port. The power converter also comprises a capacitor, whereina first node of the capacitor is coupled to the intermediate point.Furthermore, the power converter comprises a first diode element,wherein a first node of the first diode element is coupled to the inputport and wherein a second node of the first diode element is coupled tothe inductor point. The power converter also comprises a second diodeelement, wherein a first node of the second diode element is coupled tothe inductor point, and wherein a second node of the second diodeelement is coupled to the output port. In addition, the power convertercomprises an inductor, wherein a first node of the inductor is coupledto a second node of the capacitor and wherein a second node of theinductor is coupled to the inductor point.

According to a further aspect, a method for operating a power converteris described. The method comprises operating the power converter indifferent operation states to provide power at the output port of thepower converter.

A method comprises a first operation state of the power converter,closing a first switch, which is arranged between the input port and acapacitor of the power converter, to at least partially charge thecapacitor. Furthermore, the method may comprise, in the first operationstate, opening the second switch, which is arranged between thecapacitor and an inductor of the power converter, wherein the inductoris coupled to the output port, to decouple the capacitor from the outputport.

In addition, the method may comprise a subsequent second operation stateof the power converter, opening the first switch to decouple thecapacitor from the input port, and closing the second switch to at leastpartially discharge the capacitor via the inductor to the output port.

It should be noted that the methods and systems including its preferredembodiments as outlined in the present document may be used stand-aloneor in combination with the other methods and systems disclosed in thisdocument. In addition, the features outlined in the context of a systemare also applicable to a corresponding method. Furthermore, all aspectsof the methods and systems outlined in the present document may bearbitrarily combined. In particular, the features of the claims may becombined with one another in an arbitrary manner.

In the present document, the term “couple” or “coupled” refers toelements being in electrical communication with each other, whetherdirectly connected e.g., via wires, or in some other manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained below in an exemplary manner with referenceto the accompanying drawings.

FIG. 1A shows a circuit diagram of an example step-down power converter.

FIG. 1B shows a further circuit diagram of an example step-down powerconverter.

FIG. 2 shows an example output current of the power converter of FIGS.1A and 1B.

FIG. 3 shows a circuit diagram of an example multi-phase powerconverter.

FIG. 4 shows an example output current of the power converter of FIG. 3

FIG. 5 shows a circuit diagram of an example power converter comprisingan adjustable capacitor.

FIG. 6 shows an example output current for the power converter of FIG.5.

FIG. 7 shows a circuit diagram of an example step-up power converter.

FIG. 8 shows a flow chart of an example method for operating a powerconverter.

DETAILED DESCRIPTION

As outlined above, the present document is directed at providing anefficient power converter, which is configured to provide relativelyhigh voltage conversion ratios.

FIG. 1A shows a circuit diagram of a (step-down or buck) power converter100, which is configured to convert an input voltage Vin at an inputport 111 into an output voltage Vout at an output port 112. The powerconverter 100 comprises a first switch 101 (e.g. a metaloxidesemiconducator, MOS, transistor) and a second switch 102 (e.g. a MOStransistor). A first node (e.g. the source or drain) of the first switch101 is directly coupled to the input port 111, and a second node (e.g.the drain or source) of the first switch 101 is directly coupled to afirst node (e.g. the source or drain) of the second switch 102. A secondnode (e.g. the drain or source) of the second switch 102 is directlycoupled to an inductor 104 of the power converter 100, wherein theinductor 104 is coupled to the output port 112.

The power converter 100 comprises a serial arrangement of diodes 106,107 (also referred to herein as diode elements), which are arrangedbetween the second node of the second switch 102 and a reference port(e.g. ground). In addition, the power converter 100 comprises acapacitor 103, which is arranged between the second node of the firstswitch 101 and the midpoint between the first diode 106 and the seconddiode 107.

In addition, the power converter 100 may comprise an output capacitor105, which is arranged between the output port 112 and the referenceport. The output capacitor 105 is configured to smoothen voltagevariations at the output port 112. Furthermore, the power converter 100may comprise a (third) diode 108 arranged between the second node of thesecond switch 102 and the reference port.

Hence, the power converter 100 comprises an LC tank (comprising thecapacitor 103 and the inductor 104, which are arranged in series), inorder to transfer power from the input port 111 to the output port 112.The timing for controlling the switches 101, 102 may depend on the timeconstant of the LC tank, i.e. the timing may depend on the inductance Lof the inductor 104 and/or on the capacitance C of the capacitor 103.

The power converter 100 may be operated in two operation states, whereinthe operation states may be controlled using the control signals 121,122, which are applied to the gates or control nodes of the switches101, 102. During a first operation state, the first switch 101 is on andthe second switch 102 is off. When the first switch 101 is turned on,current flows from the input port 111 to the capacitor 103, through the(forward biased) first diode 106, through the inductor 104 to the outputport 112. Once the capacitor 103 is charged to the input voltage Vin,the current flow stops. Hence, the waveform of the input current (at theinput port 111) corresponds to a half sinusoid.

During the second operation state, the energy, which is stored withinthe capacitor 103, is provided to the output port 112. During the secondstate the first switch 101 is off, and the second switch 102 is turnedon. As a result of this, current flows from the reference port throughthe second diode 107, through the capacitor 103, through the secondswitch 102, through the inductor 104 to the output node 112. No currentis provided from this input port 111 during the second operation state.

The power converter 100 may be controlled by alternating the firstoperation state and the second operation state during a sequence ofcycles. Each cycle may comprise a (single) first time interval, duringwhich the power converter 100 is in the first operation state, and a(single) second time interval, during which the power converter 100 isin the second operation state. The cycles may or may not be repeated ata cycle rate, wherein the cycle rate typically depends on the outputload current, the input voltage, the output voltage and/or thetemperature.

FIG. 1B shows a further circuit diagram of a power converter 100,wherein FIG. 1B explicitly indicates that the diodes 106, 107, 108 maybe implemented using active diodes and/or switches.

It should be noted that the switches 101, 102, 106, 107, 108 of thepower converter 100 may be implemented using MOS transistors, notablyoptimised MOS transistors. Alternatively, or in addition, the switches101, 102, 106, 107, 108 may (each) be implemented by a cascode of a highvoltage switch and a low voltage switch, where the low voltage switchmay be driven from the output of the converter 100 for improvedefficiency.

FIG. 2 shows the output current 212 provided at the output port 112 ofthe power converter as a function of time t. It can be seen that theoutput current 212 comprises a half sinusoid for each first operationstate 201 and for each second operation state 202. The output current212 is drawn from the input port 111 (e.g. from a battery or a supplyattached to the input port 111) when the power converter 100 is in thefirst operation state 201. This can be seen from the input current 211which is also shown in FIG. 2. On the other hand, no current is drawnfrom the input port 111 when the power converter 100 is in the secondoperation state 202. Furthermore, FIG. 2 illustrates an example controlsignal 121 for the first switch 101 (reference numeral 213) and anexample control signal 122 for the second switch 102 (reference numeral214).

It should be noted that in contrast to other switched-mode powerconverter topologies, the topology shown in FIGS. 1A and 1B does notrequire a first operation state 201 to be followed directly by a secondoperation state 202. Alternatively, or in addition, the duration ofsubsequent cycles may be varied, depending on the current and/or energyneeds at the output port 112. If the energy needed at the output port112 is fulfilled by the first operation state 201, the second operationstate 202 does not need to be initiated. The energy remains stored inthe capacitor 103 and when energy is again requested at the output port112, an energy transfer using the second operation state 202 may beinitiated.

In order to provide a power converter 100 having relatively highefficiency, the diodes 106, 107, 108 are preferably implemented usingswitches (notably transistors) and/or active diodes. Alternatively, orin addition, zero voltage switching (ZVS) may be implemented for thefirst switch 101. This may be achieved in a reliable manner by operatingthe power converter 100 such that the first operation state 201 isdirectly followed by the second operation state 202. Hence, it may bebeneficial to operate the power converter 100 repeatedly usingalternating first and second operation states 201, 202, notably for lowpower circuits.

FIG. 3 shows a power converter 100 comprising multiple phases 331, 332in conjunction with a single inductor 104. The power converter 100comprises a first phase 331 comprising a first set of switches 101, 102,a first capacitor 103 and a first arrangement of diodes 106, 107.Furthermore, the power converter 100 comprises a second phase 332 whichis arranged in parallel to the first phase 331 and which is designed inthe same manner as the first phase 331, comprising a second set ofswitches 301, 302, a second capacitor 303 and a second arrangement ofdiodes 306, 307.

The different phases 331, 332 of the power converter 100 are preferablyoperated in a phase-shifted or time-shifted manner with respect to oneanother, in order to reduce the ripple current within the inductor 104.Hence, the control signals 221, 222 of the first phase 331 and thecontrol signals 321, 322 of the second phase 332 may be phase-shiftedwith respect to one another. In particular, the first phase 331 may beoperated in the first operation state 201, and subsequently or delayed,the second phase 332 may be operated in the first operation state 201.Subsequently, the first phase 331 may be operated in the secondoperation state 202, and subsequently or delayed, the second phase 332may be operated in the second operation state 202.

FIG. 4 shows the output current 212 of the multi-phase power converter100 of FIG. 3. The output current 212 comprises a succession of firstpeaks 401 corresponding to operation of the first phase 331 and secondpeaks 402 corresponding to operation of the second phase 332. It can beseen that by increasing the number of phases 331, 332 and/or byincreasing the cycle rate and/or the repetition frequency, the ripple ofthe output current 212 can be reduced.

FIG. 5 shows a power converter 100 which comprises a capacitor 103having an adaptable capacitance C. In the illustrated example, thecapacitance of the capacitor 103 may be adapted by arranging one or moreadditional capacitors 503 in parallel to the capacitor 103 usingswitches 504. The capacitance may e.g. be varied between 100 pF and 500pF (if integrated in silicon). The one or more capacitors 103, 503 maybe implemented as on-chip capacitors.

FIG. 6 illustrates the output current 212 for the different capacitorvalues. It can be seen that the current peaks 601, 602, 603 increasewith increasing capacitor values or capacitance C.

The power converter 100 comprises a control unit 151 which is configuredto operate the power converter 100, notably the switches 101, 102 of thepower converter 100, in dependence of the output voltage Vout at theoutput port 112, e.g. in order to regulate the output voltage to atarget voltage. The regulation may be performed by

-   -   adapting the repeating frequency and/or the cycle rate of a        cycle comprising the first and the second operation states 201,        202;    -   activating and/or deactivating one or more phases 331, 332 of        the power converter 100; and/or    -   adapting the capacitance of the one or more capacitors 103 of        the power converter 100.

FIG. 7 shows a circuit diagram of a step-up or boost power converter100. The power converter 100 comprises a first switch 101 having a firstnode that is directly coupled to the input port 111 and having a secondnode which is directly coupled to the first node of the second switch102. The second node of the second switch 102 is directly coupled to thereference port (e.g. ground). Furthermore, the second node of the firstswitch 101 is directly coupled to the capacitor 103 which is arranged inseries with the inductor 104.

Furthermore, the power converter 100 of FIG. 7 comprises a first diode106 which is directly coupled to the input port 111 and which isdirectly followed by a second diode 107, which is directly coupled tothe output port 112. The inductor 104 is directly coupled to themidpoint 114 between the first diode 106 and the second diode 107.

The power converter 100 of FIG. 7 may be operated in a first operationstate, during which the first switch 101 is off and during which thesecond switch 102 is on. As a result of this, current is flowing fromthe input port 111, through the first diode 106, through the inductor104, through the capacitor 103, through the second switch 102 to thereference port, as well as from the input port 111, through the firstdiode 106, through the second diode 107 to the output port 112. Duringthe first operation state energy is stored in the inductor 104 and inthe capacitor 103.

Furthermore, the power converter 100 of FIG. 7 may be operated in asecond operation state, during which the first switch 101 is on andduring which the second switch 102 is off. During this state, the firstdiode 106 is reverse biased. Current is flowing from the input port 111through the first switch 101, through the capacitor 103, through theinductor 104, through the second diode 107 to the output port 112.

The power converter 100 may be operated in an alternating manner in thefirst operation state and in the second operation state (as outlinedabove for the step-down power converter 100).

Hence, a DC-DC converter topology is described. The DC-DC powerconverter 100 comprises a capacitor 103 arranged in series with aninductor 104, which may be separated by a unidirectional switch (i.e.the first diode 106) to enable energy transfer in only one direction.The power converter 100 may make use of a multi-phase implementationusing only a single inductor 104. Alternatively, or in addition, one ormore additional capacitive storage elements 503 parallel to the firstcapacitor 103 may be used.

Furthermore, a method for driving a dc-dc converter topology under lowload is described. Using a high-side switch 101, a current flow via theinternal capacitor 103 to the output port 112 is enabled, therebycharging the capacitor 103 and reducing the inductor current through theinductor 104 to zero. As a result of this, the low-side switch 102 doesnot need to be enabled. Hence, a reduced amount of charge may bedelivered to the output port 112, thereby leading to reduced ripple.

For improved efficiency, the turn-on of the low side switch 102 may befollowed by the turn-on of the high side switch 101. As a result ofthis, ZVS may be achieved for the high-side switch 101.

In particular, the following aspects have been described:

-   -   A buck topology to achieve a relatively large conversion ratio        without the need for a tight control on timing of the high-side        switch 101 and/or the other switches;    -   A buck topology for which a multiphase scheme can be implemented        using a single inductor 104;    -   A buck topology for which the maximum input current may be        limited by the value of the capacitor 103 and/or the inductor        104;    -   A switching topology for which the timing for the switch control        may be defined by the inductor value and/or the capacitor value;    -   A buck topology for which a turn-on of the low-side switch 102        does not have to immediately follow a turn-on of the high-side        switch 101;    -   A buck topology for which energy can be stored within the power        converter 100;    -   A buck topology for which energy stored within the power        converter 100 may be provided on demand, if the output port 112        requests energy; possibly no energy needs to be provided from        the input port 111; and/or    -   A switching topology capable of operating with inductor and        capacitor values that can be implemented on die, and/or which        exhibit relaxed timing control for the switches 101, 102.

The LC tank of the power converter 100 may have the function of a 2^(nd)order filter at the output of the power converter 100. This filter maybe converted to a fourth order filter by splitting the inductor 104 intotwo separate inductors and by adding an additional capacitor at themid-point between the inductors. By doing this, the ripple current atthe output port 112 can be further reduced.

Hence, a (DC-DC) power converter 100 configured to provide energy at anoutput port 112 based on energy provided at an input port 111 isdescribed. The power converter 100 may be configured to performstep-down conversion, such that the output voltage at the output port112 is smaller than the input voltage at the input port 111. The inputport 111 and/or the output port 112 may be operated relative to thereference port. In particular, the input voltage and/or the outputvoltage may be indicated relative to the reference potential at thereference port (e.g. ground). The power converter 100 may be designed asshown in FIG. 1A, 1B, 3, or 5.

The power converter 100 comprises a first switch 101, wherein a firstnode of the first switch 101 is (directly) coupled to the input port 111and wherein a second node of the first switch 101 is (directly) coupledto an intermediate point 113. Furthermore, the power converter 100comprises a second switch 102, wherein a first node of the second switch102 is (directly) coupled to the intermediate point 113 and wherein asecond node of the second switch 102 is (directly) coupled to aninductor point 114. The switches 101, 102 may be MOS transistors.

In addition, the power converter 100 comprises a capacitor 103, whereina first node of the capacitor 103 is (directly) coupled to theintermediate point 113.

Furthermore, the power converter 100 comprises a first diode element106, wherein a first node of the first diode element 106 is (directly)coupled to a second node of the capacitor 103 and wherein a second nodeof the first diode element 106 is (directly) coupled to the inductorpoint 114. The first diode element 106 may be configured to enable acurrent from the first node to the second node, and to block a currentfrom the second node to the first node. The first diode element 106 maybe implemented using one or more switches which are operated to providea diode function.

Furthermore, the power converter 100 comprises a second diode element107, wherein a first node of the second diode element 107 is (directly)coupled to the reference port, and wherein a second node of the seconddiode element 107 is (directly) coupled to the second node of thecapacitor 103. The second diode element 107 may be configured to enablea current from the first node to the second node, and to block a currentfrom the second node to the first node. The second diode element 107 maybe implemented using one or more switches, which are operated to providea diode function.

In addition, the power converter 100 comprises a (single) inductor 104,wherein a first node of the inductor 104 is (directly) coupled to theinductor point 114 and wherein a second node of the inductor 104 is(directly) coupled to the output port 112.

Hence, a power converter 100 is described which comprises a serialarrangement of an inductor 104 and a capacitor 103, thereby enablingrelatively large voltage conversion ratios in an efficient manner.

The power converter 100 may comprise a control unit 151 which isconfigured to operate the power converter 100 in different operationstates (or operation modes) 201, 202 to provide (regulated) power at theoutput port 112. The plurality of different operation states 201, 202may comprise a first operation state 201, wherein within the firstoperation state 201 the first switch 101 is closed or ON and the secondswitch 102 is open or OFF. Furthermore, the plurality of differentoperation states 201, 202 may comprise a second operation state 202,wherein within the second operation state 202 the first switch 101 isopen or OFF and the second switch 102 is closed or ON. The use of theseoperation states 201, 202 enables the provision of power in a flexibleand efficient manner.

The control unit 151 may be configured to detect that energy isrequested at the output port 112. This may be detected e.g. due to adrop of the output voltage at the output port 112 (e.g. because theoutput voltage falls below a pre-determined lower voltage threshold). Inreaction to this, the power converter 100 may be operated in the firstoperation state 201, to provide energy (directly) from the input port111 to the output port 112, and to charge energy from the input port 111to the capacitor 103. As a result of this, power may be provided in arapid manner.

The control unit 151 may be configured to detect that no further energyis required at the output port 112, while the power converter 100 isoperated in the first operation state 201. This may be detected e.g. dueto a rise of the output voltage at the output port 112 (e.g. because theoutput voltage rises above a pre-determined upper voltage threshold). Inreaction to this, the power converter 100 may be maintained in the firstoperation state 201 and/or further operation of the power converter 100in the second operation state 202 may be suspended. In other words, thestored energy within the capacitor 103 may be maintained within thecapacitor 103, without the need for continuing operation of the powerconverter 100 with the second operation state 202. By doing this, theflexibility and efficiency of the power converter 100 may be increased.

The control unit 151 may be configured to detect that energy isrequested at the output port 112. This may be detected e.g. due to adrop of the output voltage at the output port 112 (e.g. because theoutput voltage falls below a pre-determined lower voltage threshold).Furthermore, it may be determined that the power converter 100 has(previously) been and/or is being operated in the first operation state201. In other words, it may be determined that the capacitor 103 ischarged. In reaction to this, the power converter 100 may be operated inthe second operation state 202, to provide energy stored within thecapacitor 103 to the output port 112. Hence, energy may be provided tothe output port 112 in a flexible and efficient manner.

The first switch 101, the second switch 102, the capacitor 103, thefirst diode element 106 and the second diode element 107 may form aphase 331 of the power converter 100, wherein the phase 331 is arrangedbetween the input port 111 and the inductor point 114. The powerconverter 100 may comprise a plurality of different phases 331, 332,which are arranged in parallel to one another between the input port 111and the inductor point 114. The different phases 331, 332 may eachcomprise a respective first switch 101, 301, a respective second switch102, 302, a respective capacitor 103, 303, a respective first diodeelement 106, 306 and a respective second diode element 107, 307. Thedifferent phases 331, 332 may exhibit the same structure. Hence, amulti-phase power converter 100 may be provided.

The multi-phase power converter 100 may comprise only a single inductor104 and/or a joint inductor 104 between the inductor point 114 and theoutput port 112 for the plurality of different phases 331, 332, therebyproviding an efficient power converter 100 with reduced current ripple.

The control unit 151 may be configured to operate the plurality ofdifferent phases 331, 332 phase-shifted with respect to one another,such that peaks of output currents 212 provided by the different phases332, 332 at the output port 112 are distributed over time and/or do notcoincide. By doing this, the current ripple at the output port 112 maybe reduced.

The capacitance value of the capacitor 103 may be adjustable (e.g. usinga matrix of capacitors 103, 503, as shown in FIG. 5). The control unit151 may be configured to adapt the capacitance value of the capacitor103 during operation of the power converter 100, thereby furtherincreasing the flexibility and/or the efficiency of the power converter100.

The control unit 151 may be configured to determine a voltage indicationof the output voltage of the energy provided at the output port 112. Thevoltage indication may be determined using voltage sensing means (e.g. avoltage divider). The control unit 151 may be configured to operate thepower converter 100 in dependence of the voltage indication, notably toregulate the output voltage to a target voltage. By doing this, aregulated output voltage may be provided for supplying electrical powerto one or more devices at the output port 112.

In particular, the control unit 151 may be configured to adapt the cyclerate for repeating a cycle comprising a plurality of different operationstates of the power converter 100 in dependence of the voltageindication. Alternatively, or in addition, the control unit 151 may beconfigured to adapt the number of active phases 331, 332 from aplurality of different phases 331, 332 of the power converter 100 independence of the voltage indication. Alternatively, or in addition, thecontrol unit 151 may be configured to adapt the capacitance value of thecapacitor 103 in dependence of the voltage indication. Hence, the powerconverter 100 may be adapted in various different manners to provide aprecise regulation of the output voltage.

The control unit 151 may be configured to set one or more succeedingtime instants for changing between different operation states 201, 202in dependence of a time constant which depends on the capacitance C ofthe capacitor 103 and the inductance L of the inductor 104, notably onL*C. By doing this, an efficient power conversion may be provided.

The power converter 100 may comprise an LC filter arranged between theinductor 104 and the output port 112. The LC filter may comprise afilter inductor and a filter capacitor, wherein the filter inductor isarranged in series with the inductor of the power converter and whereinthe filter capacitor is arranged to couple the midpoint between theinductor and the filter inductor to the reference port. The totalinductance of the power converter may be provided by the sum of theinductance of the inductor and the filter inductor.

In particular, the power converter 100 may comprise an output capacitor105, which is coupled to the output port 112. The output capacitor 105and the inductor 104 may be split up in several partial capacitors andseveral partial inductors to form a fourth or higher order outputfilter. By making use of an LC filter, the ripple of the output currentmay be reduced.

As indicated above, the first diode element 106, the second diodeelement 107 and/or the third diode element 108 may each be implementedusing one or more switches. In this case, the power converter 100 may beadapted to provide relatively low power conversion ratios (e.g. between1 and 0.5) in an efficient manner. In particular, the first diodeelement 106 and the second diode element 107 may be maintained open.Furthermore, the second switch 102 may be maintained closed. The firstswitch 101 and the third diode element 108 (being implemented using aswitch) may then be operated to provide a switched-mode power converter.

Hence, the first diode element 106 may be implemented using a switch,and the second diode element 107 may be implemented using a switch. Asoutlined above, the power converter 100 may comprises a third diodeelement 108, which is configured to couple the inductor point 114 to thereference port. The third diode element 108 may be forward biased in thedirection from the reference port to the inductor port 114. The thirddiode element 108 may also be implemented using a switch.

In order to provide relatively low conversion ratios, the control unit151 may be configured to maintain the first diode element 106 and thesecond diode element 107 open, and maintain the second switch 102closed. Furthermore, the control unit 151 may be configured to performpower conversion between the input port 111 and the output port 112 byalternatingly switching on and off the first switch 101 and the thirddiode element 108. Hence, the power converter 100 may also be used forrelatively low power conversion ratios.

In addition, a power converter 100 (notably a step-up or boost powerconverter) configured to provide energy at an output port 112 based onenergy provided at an input port 111 is described. The aspects and/orfunctions described for the (step-down) power converter 100 are alsoapplicable to the (step-up) power converter 100. An example step-uppower converter 100 is shown in FIG. 7.

The power converter 100 comprises a first switch 101, wherein a firstnode of the first switch 101 is (directly) coupled to the input port 111and wherein a second node of the first switch 101 is (directly) coupledto an intermediate point 113. Furthermore, the power converter 100comprises a second switch 102, wherein a first node of the second switch102 is (directly) coupled to the intermediate point 113 and wherein asecond node of the second switch 102 is (directly) coupled to areference port.

In addition, the power converter 100 comprises a capacitor 103, whereina first node of the capacitor 103 is (directly) coupled to theintermediate point 113.

The power converter 100 further comprises a first diode element 106,wherein a first node of the first diode element 106 is (directly)coupled to the input port 111 and wherein a second node of the firstdiode element 106 is (directly) coupled to the inductor point 114. Inaddition, the power converter 100 comprises a second diode element 107,wherein a first node of the second diode element 107 is (directly)coupled to the inductor point 114, and wherein a second node of thesecond diode element 107 is (directly) coupled to the output port 112.

Furthermore, the power converter 100 comprises an inductor 104, whereina first node of the inductor 104 is (directly) coupled to a second nodeof the capacitor 103 and wherein a second node of the inductor 104 is(directly) coupled to the inductor point 114.

FIG. 8 shows a flow chart of an example method 800 for operating a powerconverter 100 described in the present document. The method 800comprises 801, operating the power converter 100 in different operationstates 201, 202, notably to provide power at the output port 112 at aregulated output voltage.

Furthermore, a method provides energy at an output port 112 of a powerconverter 100 based on energy provided at an input port 111 of the powerconverter 100. The power converter 100 may comprise one or more of thecomponents described in the present document. In particular, the powerconverter 100 may be designed as described in the context of FIGS. 1Aand 1B.

The method comprises, in a first operating state 201 of the powerconverter 100, closing the first switch 101 which is arranged betweenthe input port 111 and a capacitor 103 of the power converter 100, to atleast partially charge the capacitor 103. Furthermore, the method maycomprise, in the first operation state 201, opening the second switch102, which is arranged between the capacitor 103 and an inductor 104 ofthe power converter 100, wherein the inductor 104 is coupled to theoutput port 112, to decouple the capacitor 103 from the output port 112.

In addition, the method may comprise, in a subsequent second operationstate 202 of the power converter 100, opening the first switch 101 todecouple the capacitor 103 from the input port 111, and closing thesecond switch 102 to at least partially discharge the capacitor 103 viathe inductor 104 to the output port 112.

The current waveform at the input and the output of the power converter100 may be half sinusoid or an overlay of a plurality of half sinusoids(in case of a multi-phase power converter 100) as illustrated in FIGS.2, 4 and 6. The peak of the input current pulses may vary as the load atthe output port 112 increases.

The power converter 100 described in the present document may be usedwithin an LDO (low-drop out) voltage regulator. As a result, relativelyhigh power efficiency with a relatively high voltage conversion ratiomay be achieved (e.g. 60% efficiency for Vin of 5V and Vout of 1V).Furthermore, EMI requirements may be reduced.

It should be noted that the description and drawings merely illustratethe principles of the proposed methods and systems. Those skilled in theart will be able to implement various arrangements that, although notexplicitly described or shown herein, embody the principles of theinvention and are included within its spirit and scope. Furthermore, allexamples and embodiment outlined in the present document are principallyintended expressly to be only for explanatory purposes to help thereader in understanding the principles of the proposed methods andsystems. Furthermore, all statements herein providing principles,aspects, and embodiments of the invention, as well as specific examplesthereof, are intended to encompass equivalents thereof.

What is claimed is:
 1. A power converter configured to provide energy atan output port based on energy provided at an input port; wherein thepower converter comprises, a first switch, wherein a first node of thefirst switch is coupled to the input port and wherein a second node ofthe first switch is coupled to an intermediate point; a second switch,wherein a first node of the second switch is coupled to the intermediatepoint and wherein a second node of the second switch is coupled to areference port; a capacitor, wherein a first node of the capacitor iscoupled to the intermediate point; a first diode element, wherein afirst node of the first diode element is coupled to the input port andwherein a second node of the first diode element is coupled to aninductor point; a second diode element, wherein a first node of thesecond diode element is coupled to the inductor point, and wherein asecond node of the second diode element is coupled to the output port;and an inductor, wherein a first node of the inductor is coupled to asecond node of the capacitor and wherein a second node of the inductoris coupled to the inductor point.
 2. The power converter of claim 1,wherein the power converter comprises a control unit; and the controlunit is configured to operate the power converter in different operationstates to provide power at the output port.
 3. The power converter ofclaim 2, wherein the control unit is configured to operate the powerconverter in a first operation state; and within the first operationstate the first switch is open or OFF and the second switch is closed orON.
 4. The power converter of claim 2, wherein the control unit isconfigured to operate the power converter in a second operation state;and within the second operation state the first switch is closed or ONand the second switch is open or OFF.
 5. The power converter of claim 3,wherein the control unit is configured to detect that energy isrequested at the output port; and operate the power converter in thefirst operation state, to provide energy from the input port to theoutput port, and to charge energy from the input port to the capacitor.6. The power converter of claim 5, wherein the control unit isconfigured to detect that no further energy is required at the outputport, while the power converter is operated in the first operationstate; and maintain the power converter in the first operation stateand/or suspend operating the power converter in the second operationstate.
 7. The power converter of claim 3, wherein the control unit isconfigured to detect that energy is requested at the output port; anddetermine that the power converter has been and/or is being operated inthe first operation state; and operate the power converter in the secondoperation state, to provide energy stored within the capacitor to theoutput port.
 8. The power converter of claim 2, wherein the control unitis configured to determine a voltage indication of an output voltage ofthe energy provided at the output port; and operate the power converterin dependence of the voltage indication, to regulate the output voltageto a target voltage.
 9. The power converter of claim 8, wherein thecontrol unit is configured to adapt a cycle rate for repeating a cyclecomprising a plurality of different operation states of the powerconverter; adapt a number of active phases from a plurality of differentphases of the power converter; and/or adapt a capacitance value of thecapacitor in dependence of the voltage indication.
 10. The powerconverter of claim 2, wherein the control unit is configured to set oneor more succeeding time instants for changing between differentoperation states in dependence of a time constant, which depends on acapacitance of the capacitor and an inductance of the inductor.
 11. Thepower converter of claim 1, wherein the first switch, the second switch,the capacitor, the first diode element and the second diode element forma phase of the power converter; and the power converter comprises aplurality of phases, which are arranged in parallel to one another. 12.The power converter of claim 11, wherein the power converter comprisesonly a single inductor and/or a joint inductor between the inductorpoint and the capacitor for the plurality of different phases.
 13. Thepower converter of claim 11, wherein the power converter comprises acontrol unit; and the control unit is configured to operate theplurality of different phases phase-shifted with respect to one another,such that peaks of output currents provided by the different phases atthe output port are distributed over time and/or do not coincide. 14.The power converter of claim 1, wherein a capacitance value of thecapacitor is adjustable; and the power converter comprises a controlunit configured to adapt the capacitance value of the capacitor duringoperation of the power converter.
 15. The power converter of claim 1,wherein the first diode element and/or the second diode element areconfigured to enable a current from the respective first node to therespective second node, and to block a current from the respectivesecond node to the respective first node; and/or the first diode elementand/or the second diode element are implemented using one or moreswitches which are operated to provide a diode function.
 16. The powerconverter of claim 1, wherein the power converter comprises an outputcapacitor which is coupled to the output port; and the output capacitorand the inductor are split up in several partial capacitors and severalpartial inductors to form a fourth or higher order output filter. 17.The power converter of claim 1, wherein the first diode element isimplemented using a switch; the second diode element is implementedusing a switch; the power converter comprises a third diode elementwhich is configured to couple the inductor point to the reference port;wherein the third diode element is implemented using a switch; the powerconverter comprises a control unit; and the control unit is configuredto maintain the first diode element and the second diode element open;maintain the second switch closed; perform power conversion between theinput port and the output port by alternatingly switching on and off thefirst switch and the third diode element.
 18. A method for operating apower converter according to claim 1; wherein the method comprises,operating the power converter in different operation states to providepower at the output port at a regulated output voltage.
 19. A method forproviding energy at an output port of a power converter according toclaim 1 based on energy provided at an input port of the powerconverter; wherein the method comprises, in a first operating state ofthe power converter, opening the first switch; and closing the secondswitch, to store energy in the capacitor; and in a subsequent secondoperation state of the power converter, closing the first switch; andopening the second switch to at least partially discharge the capacitorvia the inductor to the output port.